21150401121565 has 32 divisors (see below), whose sum is σ = 28120510735200. Its totient is φ = 15202251177984.

The previous prime is 21150401121541. The next prime is 21150401121569. The reversal of 21150401121565 is 56512110405112.

It can be written as a sum of positive squares in 16 ways, for example, as 33315740676 + 21117085380889 = 182526^2 + 4595333^2 .

It is a cyclic number.

It is not a de Polignac number, because 21150401121565 - 2²⁷ = 21150266903837 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21150401121565.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21150401121569) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 63277540 + ... + 63610909.

It is an arithmetic number, because the mean of its divisors is an integer number (878765960475).

Almost surely, 2^{21150401121565} is an apocalyptic number.

It is an amenable number.

21150401121565 is a deficient number, since it is larger than the sum of its proper divisors (6970109613635).

21150401121565 is a wasteful number, since it uses less digits than its factorization.

21150401121565 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 126888561.

The product of its (nonzero) digits is 12000, while the sum is 34.

Adding to 21150401121565 its reverse (56512110405112), we get a palindrome (77662511526677).

The spelling of 21150401121565 in words is "twenty-one trillion, one hundred fifty billion, four hundred one million, one hundred twenty-one thousand, five hundred sixty-five".